84 FLH... I hit the start button, it cranks, then comes a loud knock (bang), then a grinding on the starter motor likes it is working overtime to start. The grinding gets ever so slow if I continue to crank (almost like its binding).

I took apart the starter motor. It has a new armature, new brushes. No problems with solenoid. Pulled the starter shaft and replaced it with an OEM I have had sitting on the shelf, cleaned plates (steel and fiber), did a reset, made sure battery was fully charged, reassembeled, and...the same damn thing all over again.

When I had the clutch apart I pulled the plugs and the motor turns over without any hesitation or binding.

That said...I am thinking that I need to check my valve train? (Cold motor ... no load on the valve train cuz lifters haven't pumped up)

Pushrod adjustment is an easy check. How do I check to see if my lifters are good (running Jims).

Suggestions please.

This is driving me nuts. Rebuilt the motor at just over 50K and over 15K miles later it has always been reliable. Trips to North/South Dakota, Colorado and the Northwest (Washington, Oregon, Montana & Idaho) with zero problems or issues.

 

Usually the only thing that has the ability to grind or even Knock is the bendix clutch slips then catches

i made a tool from an old broken primary and cut the corner leaving two Allens and the bearing in place - you then can see first hand when using a hand held starter button what working and whats not

 

cranks fine with the plugs out, a weak battery may not be detected. I would not overlook the simple stuff first, What is you voltage drop when you crank?

 

Both absolutely Great suggestions... Certainly a Good Start
The cut-up outer primary can be a Life Saver...

 

as said, it sounds like the starter clutch is breaking down under load, only meant to spin one way but when buggered they sound bad & the motor either spins slow & in jumps & jolts or doesnt turn the motor but sounds like hell,.
a very comon problem on shovels, i musta changed 10-15 of them over te years, 'ALLBALLS' make a good strong replacement All ***** Racing Starter Clutch Assembly 79-2109 FL/FX 1980 - 1988 | eBay

 

ive seen that done before when running a open belt and elec start. a great idea

 

Never done that... I use it for a Tool and troubleshooting!!!

 

I have been chasing the starter bendix as of late and found they are ripping everyone off - paid 80 bucks and got a 35 dollar one

 

I had a very similar problem recently.
When I jumped from the battery pos straight to the small terminal on the solenoid, all worked correctly.
Now I knew I had a low voltage issue. So I worked forward from the battery, checking for 12 volts at each step.
I finally discovered that I had 12v on the hot side of the starter switch on the handlebar, but only 5v on the other when pushing the button. So I cleaned the switch with electronic cleaning spray while working the button in and out and rotating, and sure enough I was able to achieve 12v on both sides. The starter now spins perfectly.
It may be worth a look see on your project.

 

12.0V or 12.6+ volts???? yes it Very Much Matters...
BTW if you can clean that little switch, that is Great, as the ones available today are Crap... maybe Not that Good...plus kinda mean to replace...